Co-phasing experiment of a segmented mirror using a combined broadband and two-wavelength algorithm

Area of Science:

• Optics and Photonics
• Optical Engineering
• Adaptive Optics

Background:

• Segmented mirrors are crucial for large-aperture optical systems.
• Accurate co-phasing of mirror segments is essential for optimal performance.
• Piston error, a critical parameter, requires precise measurement and correction.

Purpose of the Study:

• To develop and validate a novel combined phasing algorithm for segmented mirrors.
• To achieve long-range, high-precision, and fast detection of piston error.
• To demonstrate the algorithm's effectiveness in an active optics experimental system.

Main Methods:

• Integration of a broadband phasing algorithm with a two-wavelength phasing algorithm.
• Utilizing a Shack-Hartmann sensor and piezoelectric actuators for fine co-focusing.
• Experimental setup with a four-hexagonal-segment mirror (100 mm flat-to-flat, 2000 mm radius of curvature).

Main Results:

• Broadband phasing reduced piston error to the micrometer level.
• Two-wavelength phasing further reduced piston error to zero.
• Achieved measurement accuracy better than 26 nm and adjustment accuracy of approximately 55 nm.

Conclusions:

• The combined phasing algorithm effectively measures and adjusts piston error in segmented mirrors.
• The developed active optics system validates the algorithm's practical applicability.
• This technique is valuable for co-phasing measurement and adjustment in advanced optical systems.